Looking at two never-fired 12g SKB Model 100 doubles bought in the 70s Serial Numbers S5128523 and S1701063. SKB site doesn't recommend using steel in older models. Permissible for screw-in-chokes with two letters preceding numbers. The older doubles without screw-ins? My 20g a Model 500 o/u of same period is chrome-lined.

According to Don Zutz in The Ducks Unlimited Guide to Shotgunning much depends on method or barrel jointing (brazed is preferred to soldered) choke constrictions and size of shot used (smaller shot is better then larger pellets). I did see Model 100 or Model 200 in fine exterior shape with scratches in choke area of the bore and could not figure out how those got there (neither could people at shop I seen it at).
Our shooting expert HomelessJoe suspects that much of barrel damage occurred when steel shot was first introduced. The shells did not have appropriate shot cups nor were not well water-proofed. Moisture would get in leading to shot clumping which did the actual barrel damage. I suspect he is correct on this.

my gunsmith with over 60 years of experience suggests not to use steel in barrels made prior to the late eighties, as the steel is generally too soft.

however, popular wisdom indicates steel can be used without problem in browning bss and skb sxs guns made in the seventies and eighties, and with chokes no tighter than modified.

also, Russian Baikal guns made in the nineties and there after, with screw in choke tubes seem to be popular with steel shooters.

A gunsmith I know Ed with just a few years more experience than yours disagrees with that. He says that any steel made after WWII is adequate to handle steel shot. What matters is precisely what Homeless Joe is reported to have said in Jagermeister's post above. The early steel shot shells were dramatically inferior to those produced today, from waterproofing to shot cups/buffers, etc. The size of shot also makes a major difference, i.e., no shot larger than 4s through modified and no steel shot period through full chokes, etc, etc. I have a Stevens Model 311 that my Dad bought for me on my 13th birthday in February of 1962, choked modified and IC. I have shot ducks with steel 4s with it several times with absolutely no damage done to the bore or the choke/muzzle end. I have shot either Remington or Winchester steel loads.

I shoot steel through my SKB 100, a couple hundred rounds and no evidence of ill effects. Choked IC/MOD helps and I personally use 3's and 4's---all handloads with quality MultiMetal BPS wads.

Steve

I shoot steel through my SKB 100, a couple hundred rounds and no evidence of ill effects. Choked IC/MOD helps and I personally use 3's and 4's---all handloads with quality MultiMetal BPS wads.

Steve

I shoot steel 2s in my Miroku-Daly 500. It has 28" barrels with chokes opened to IC and Mod. No damage in about 10 years...Geo

Thank you. You have been generous in making comments. They've been a big help in decision-making. My nephew and I gun under sheets of salt water and now figure those under-rated Model 100s are more practical than the acclaimed Berettas we were/are still considering. We bought the SKBs for $180 each in the 70s, were seduced by the clickety-clacks and only came back to our senses with double gun.org.

King, as the old knight in the Indianna Jones movie about the Holy Grail said ".....you have chosen....wisely" I also went down that same path but thankfully returned to the One True Way of double guns almost 20 years ago. I have never looked back!!

The SKB's are not Miroku-made guns, but the Browning website says steel is fine in all of its Japanese-made guns.

I believe all the Ithaca-imported SKB's had chrome-lined bores. Not positive about the later ones. But I have shot steel through a Model 100 20ga with chokes no tighter than mod. Might be best to stick with mod or more open, for no other reason than possible patterning issues with steel through tighter chokes.

I certainly agree with that last statement Larry. My SKB 280E is choked modified and full and it is a reaalllly tight full. I keep saying I am going to have it opened up to IC and MOD and have a gunsmith that has no problems with the chrome lined bores, but I just haven't taken it to him to do.